The default mode network (DMN), traditionally seen as an internally focused system for daydreaming and planning, is proposed to be an active 'sense-making' network that combines incoming external information with prior internal knowledge to build rich, context-dependent models of unfolding situations. Review of studies using naturalistic stimuli like stories and movies shows that an individual's DMN responses are shaped both by external information accumulating over time and by personal past memories. This integration over long timescales creates a shared neural code essential for shared meaning, communication, narratives, and social communities.
The default mode network (DMN) reconfigures moment by moment to encode information about a changing environment, as shown by a new method called inter-subject functional correlation (ISFC). ISFC isolates stimulus-dependent correlations between brains exposed to the same stimulus, separating them from intrinsic neural processes and noise. In an fMRI experiment, subjects listened to an auditory narrative or temporally scrambled versions. ISFC revealed DMN correlation patterns locked to each narrative segment and specific to its meaning. These patterns were highly replicable across groups, and DMN coupling strength predicted memory of narrative segments, linking brain network dynamics to stimulus features and behavior.